Anxiety and depression predict musculoskeletal disorders in health care workers

Investigation of musculoskeletal disorders, physical activity level, sleep quality, and fatigue in health professionals with and without a history of COVID-19

BACKGROUND

Healthcare workers belong to an occupational group that is at high risk during the coronavirus 2019 (COVID-19) pandemic. The increased workload of healthcare workers and the accompanying psychosocial stress caused by the pandemic can affect musculoskeletal system disorders, physical activity status, sleep quality, and fatigue in this group.

OBJECTIVE

To investigate musculoskeletal system disorders, physical activity level, sleep quality, and fatigue in healthcare workers healthcare workers with and without a COVID-19.

METHODS

A total of 200 healthcare professionals aged 18-65 years with and without a history of COVID-19 were in the study. Data were collected between January and March 2021. A "Preliminary Evaluation Form", "Extended version of the Nordic Musculoskeletal System Questionnaire (NMQ-E)", "the International Physical Activity Questionnaire-Short Form (IPAQ-SF)" and "the Pittsburgh Sleep Quality Index (PSQI) were used for data collection".

RESULTS

It was determined that musculoskeletal system disorders did not differ significantly between healthcare workers with and without a COVID-19 history (p > 0.05). It was found that the number of people with problems in the low-back region was higher in those with a COVID-19 history (p = 0.002). In the sleep duration component, the scores of those who did not have a COVID-19 history were found to be significantly higher than those who did (p = 0.10). In other comparisons, it was determined that there was no significant difference.

CONCLUSIONS

It was found that the number of people with problems in the low-back region was higher in those with a COVID-19 history. Those without a COVID-19 history had higher scores in sleep duration parameter.

The significant association between quick return and depressive symptoms and sleep disturbances in paid workers: A nationwide survey

Objectives

Although many studies have examined the association between shift work and depression or insomnia, few studies have examined the relationship between quick return (QR) to work and depressive symptoms, regardless of shift work. Thus, in this study, we aimed to assess the association between depressive symptoms (DS)/sleep disturbances (SDs) and QR.

Methods

Data from the 6^th Korean Working Conditions Survey (2020) were used for this study. Paid workers aged between 20 and 65 years were included. DS were defined using the World Health Organization Well-Being Index (WHO-5) with a cut-off 50, and SD was defined as the occurrence of the following symptoms several times per month: difficulty in falling asleep, waking up in the middle of the night, or feeling tired even after waking up. QR was defined as "at least one case where the working interval between leaving work and the next day's work was < 11 h in the past month." Multivariable logistic regression was performed to estimate the adjusted odd ratios (aORs) and 95% confidence intervals (CIs). Mediation analysis was conducted to examine whether SD was a significant mediator in the association between QR and DS.

Results

Among the 27,554 participants, DS occurred in 8,277 patients, while SD occurred in 6,264 patients. The aORs (95% CIs) of DS and SD by QR were 2.01 (1.78-2.27) and 3.24 (2.87-3.66), respectively, after adjusting for age, gender, income, education, working hours, job status, working duration, region, shift work, and occupation. SD was a significant mediator in the association between QR and DS.

Conclusion

QR is significantly associated with DS or SD regardless of demographic factors and the working environment. The significant relationship between QR and DS may be mediated by SD.

Effects of Mobile App-Based Mindfulness Practice on Healthcare Workers: a Randomized Active Controlled Trial

Objectives

Amidst the COVID-19 pandemic, healthcare workers (HCWs) may be at greater risk of suffering from psychological distress compared to the general population. This study aimed to investigate the effects of mindfulness practice as delivered using Headspace on psychological and cognitive outcomes among HCWs in Singapore.

Methods

A total of 80 HCWs were recruited and randomly assigned to engage in either 3 weeks (10 min/day) of mindfulness practice using Headspace or an active control condition (Lumosity; involving playing cognitive games). Participants were administered several self-report measures and two working memory (digit span) tasks at pre- and post-intervention, and one-month follow-up.

Results

There were no significant between-condition changes on any outcome variables from pre- to post-intervention. From pre-intervention to 1-month follow-up, there were significantly greater improvements among Headspace participants on fear of COVID-19 (p = .005), compassion satisfaction (p = .007), trait mindfulness (p = .002), self-compassion (p = .005), sleep quality (p = .002), and the forward digit span task (p < .001). Several outcomes were mediated by increases in trait mindfulness or self-compassion.

Conclusions

Use of Headspace may lead to downstream benefits in reducing distress and improving psychological health outcomes among HCWs. The findings have implications for improving psychological support resources for HCWs amidst a pandemic.

Trial Registration

ClinicalTrials.gov (Identifier: NCT04936893).

Consequences of social distancing during the COVID-19 pandemic on the increase in perceived pain of students and professors from higher education institutions: A cross-sectional study

BACKGROUND: social distancing was implemented worldwide due to the coronavirus (COVID-19) pandemic. This impacted physical activity levels and increased the time spent in sedentary behaviors which may contributed to the emergence of increased musculoskeletal complaints. OBJECTIVE: To assess the consequences of social distancing for the increase in perceived pain of students and professors from higher education institutions. METHODS: One thousand two hundred and fifty-four participants responded to an online survey containing sociodemographic information and questions related to daily habits, physical activity profile, and musculoskeletal pain before and during the pandemic. Level of concentration, nervousness, productivity, and visual fatigue were also assessed. The primary outcome was presence of perceived pain before and during the pandemic, dichotomized between those with and without increased pain during the pandemic. RESULTS: perceived pain increased during the pandemic (p <  0.001) and was associated with females (p = 0.023; PR = 1.16; 95% CI = 1.02–1.32), income up to one minimum wage (p = 0.039; PR = 1.20; 95% CI = 1.01–1.42), no physical activity practice (p = 0.006; PR = 1.22; 95% CI = 1.06–1.40), long time in sedentary behavior (p = 0.013; PR = 3.07; 95% CI = 1.27–7.43), and electronic device usage for >  6 hours (p = 0.041; PR = 1.44; 95% CI = 1.02–2.06). Nervousness (p = 0.001) and visual fatigue (p = 0.001) increased, whereas concentration (p = 0.001) and productivity (p = 0.001) reduced during the pandemic. CONCLUSIONS: reduced physical activity practice and increased time in sedentary behavior and electronic device usage during the pandemic were associated with increased musculoskeletal pain in students and professors from higher education institutions. Decreased concentration and productivity and increased nervousness and visual fatigue were also observed during the pandemic.

Depression and Psychological Stress Among Health Workers in Remote Areas in Indonesia

Background

The Indonesian government launched the Nusantara Sehat program in 2015, under which teams of health workers were assigned to community health care centers in remote, border, and island areas for 2 years. The deployment to remote areas is likely to affect their psychological condition if they are not equipped with facilities and strong motivation. This study aimed to describe the psychological condition of health workers in remote areas in Indonesia, focusing on the proportion of the prevalence of depression and psychological stress.

Materials and Methods

This cross-sectional study was conducted between April and December of 2018. Participants were 140 health workers placed in 26 community healthcare centers in 13 provinces. Interviews were conducted by enumerators using a questionnaire that included questions from the Mini International Neuropsychiatric Interview (MINI) and Self-Reporting Questionnaire-20 (SRQ-20).

Results

Of the participants, 7.1% experienced depression and 10.0% experienced psychological stress. Motivation was related to psychological stress in participants with an odds ratio of 0,218 (95% confidence interval = 0.065–0.729, p = 0.013). Health workers with high motivation tend not to experience psychological stress compared to individuals with lower motivation.

Conclusion

Health workers with high motivation experience relatively low levels of psychological stress. To overcome stress, high motivation is needed to control psychological risk factors before and during placement.

Precarious Work Schedules and Sleep: A Study of Unionized Full-Time Workers

Unlike precarious employment which is temporary and insecure, with inadequate pay, benefits, and legal protections, precarious work schedules can affect workers with permanent full-time jobs in sectors where employment has historically been secure, well-compensated, and even unionized. Precarious work schedules - characterized by long shifts, non-daytime hours, intensity and unsocial work hours - are increasingly prevalent. Relations between precarious work schedules and poor health are not well understood, and less is known about how to attenuate this relation. We examined the indirect effects of precarious work schedules on fatigue and depressive symptoms through sleep quantity. Two moderators - schedule flexibility and sleep quality - were examined as buffers of these associations. Workers from the Departments of Correction and Transportation in a northeast state (N = 222) took surveys and reported on demographics, work schedule characteristics, schedule flexibility, sleep quality and quantity, fatigue, and depressive symptoms. Results revealed that precarious work schedules had indirect effects on fatigue and depressive symptoms through sleep quantity. Schedule flexibility moderated the relation between precarious work schedules and sleep quantity, such that workers with greater schedule flexibility had more hours of sleep. Sleep quality moderated the association between sleep quantity and fatigue and depressive symptoms, such that workers reported greater fatigue and depressive symptoms when they had poorer sleep quality. Findings have direct applicability for developing initiatives that enhance Total Worker Health® through individual and organizational changes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41542-022-00114-y.

Emotional Labor and Depressive Symptoms Among Healthcare Workers: The Role of Sleep

BACKGROUND

Depression is the second leading cause of disability worldwide. Health care workers report a higher prevalence of depressive symptoms than the general population. Emotional labor has contributed to poor health and work outcomes. However, the mechanism for the potential association between emotional labor and depressive symptoms has not been well studied. This study examines the relationship between emotional labor and depressive symptoms and whether sleep plays a role in explaining this relationship.

METHODS

In 2018, health care workers (n = 1,060) from five public sector facilities in the northeast United States participated in this cross-sectional survey. The survey included questions on participants' surface-acting emotional labor (masking one's feelings at work), depressive symptoms, sleep duration and disturbances, and socio-demographic characteristics. Multivariable linear and Poisson regression modeling were used to examine associations among variables.

FINDINGS

There was a significant association between emotional labor and depressive symptoms (β = 0.82, p < .001). Sleep disturbances, but not short sleep duration, partially mediated this association. Neither sleep variable moderated this association.

CONCLUSIONS/APPLICATION TO PRACTICE

Depressive symptoms were prevalent among health care workers and were associated with emotional masking. Sleep disturbances play an important intermediate role in translating emotional labor to depressive symptoms in these workers. Effective workplace programs are needed to reduce health care workers' emotional labor to improve their mental health. Sleep promotion should also be emphasized to mitigate the negative effect of emotional labor and promote mental wellbeing.

Development and validation of a Nurse Station Ergonomics Assessment (NSEA) tool

Background

Nurse stations are one of the primary units for supporting effective functioning of any hospital. They are important working environments that demand adherence to known ergonomic principles for the well-being of both staff and patients. The aim of this study was to develop a psychometrically tested tool for the assessment of the ergonomic conditions of nurse workstations in hospitals.

Methods

Ten hospitals, with a total of 133 nurse stations participated in this mixed-methods research. The domains and items of the tool were developed based on a literature review, an experts’ panel, and interviews with nurses.

Results

The final nurse station ergonomic assessment (NSEA) tool has good psychometric properties. Validity was assessed by face validity and content validity. Reliability was evaluated using inter-rater agreement and test-retest reliability analyses with a four-week interval between assessments. The NSEA is comprised of 64 items across eight domains: layout and location (7 items), workspace (11 items), security-safety (5 items), environmental conditions (8 items), counter (8 items), chair (13 items), desk (9 items), and monitor (3 items).

Conclusions

The NSEA adds to the literature a tool for managers to ensure they comply with legal requirements and support best practice for those working on hospital wards. The NSEA can be used to identify challenges for healthcare professionals who use nurse stations and support the execution of targeted interventions to improve human-environment interactions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12912-021-00600-8.

Different pain variables could independently predict anxiety and depression in subjects with chronic musculoskeletal pain

OBJECTIVES

Chronic, clinical pain states are often accompanied by distress such as anxiety and depression. The aim of this study was to determine if certain clinical pain variables could predict the level of anxiety and depression in subjects with musculoskeletal pain.

METHODS

Two multiple linear regression analyses were conducted on a sample consisting of 189 subjects with clinical pain with the independent pain variables of pain intensity, the influence of pain on daily activities, pain persistence, pain duration, and the number of pain locations. The dependent variables measured anxiety and depression, respectively.

RESULT

Two statistically significant models were found, where the predicted variables accounted for 37.0% of the variability in the anxiety levels and 43.7% of the variability in the depression levels. The independent variable, the influence of pain on daily activities, significantly predicted the level of anxiety. The variables, the influence of pain on daily activities and the number of pain locations, significantly predicted the levels of anxiety and depression.

CONCLUSIONS

This study showed that two different independent variables, the influence of pain on daily activities and the number of pain locations, significantly predicted the levels of depression. The predictor, the influence of pain on daily activities, significantly predicted the levels of anxiety. The knowledge gained about which specific pain variables are more likely to coexist with anxiety and depression in clinical pain states could be important in implementing holistic treatment plans for chronic pain.

[Prevalence of anxiety among health professionals in times of COVID-19: a systematic review with meta-analysis]

This study sets out to identify the prevalence of anxiety among health professionals during the COVID-19 pandemic. It involves a systematic review and meta-analysis of studies published in any language in 2020. A search was conducted in the Embase, LILACS and PubMed databases using the keywords anxiety, COVID-19, health workers, and synonyms. The estimated overall prevalence of anxiety with a 95% confidence interval was calculated using the random effects model. Of the 861 records identified, 36 articles were included in the systematic review and 35 in the meta-analysis. The overall prevalence of anxiety was 35% (95%CI: 29-40). A higher risk of anxiety was identified among women compared to men (Odds Ratio: 1.64 [95%CI: 1.47-1.84]), and in nurses, in comparison with physicians (Odds Ratio: 1.19 [95%CI: 1.07-1.33]). Being on the front line of COVID-19, being infected with coronavirus and having chronic diseases were also factors associated with a higher risk of anxiety. A high prevalence of anxiety among health professionals was observed, with higher risk among women and nurses. There is a pressing need for measures aimed at prevention of anxiety and providing early and appropriate treatment for those suffering from moderate and severe anxiety.

Mental Disorders, Musculoskeletal Disorders and Income-Driven Patterns: Evidence from the Global Burden of Disease Study 2017

Background: The aim of the present study was to use the extensive Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) database from 1990–2017 to evaluate the levels and temporal correlation trends between disability adjusted life years (DALYs) attributed to musculoskeletal (MSK) disorders, all mental disorders collectively and by mental disorder sub-category. Methods: We utilized results of the GBD 2017 to describe the correlation patterns between DALYs due to MSK disorders, mental disorders and other diseases among 195 countries. Mixed model analysis was also applied. Results: A consistent relation was reported between age-adjusted DALYs attributed to MSK and mental disorders (in total) among the 195 countries, in both sexes, for 1990 to 2017 (1990 Rho = 0.487; 2017 Rho = 0.439 p < 0.05). Distinct regional and gender correlation patterns between age-adjusted DALYs due to MSK and mental disorders were reported. No correlation was reported between DALYs due to MSK and all mental disorders collectively, among Low- or Middle-income countries. However, in High-income countries (HICs), the correlation was strong and consistent between 1990 and 2017 (1990 Rho = 0.735; 2017 Rho = 0.727, p < 0.05). Conclusions: The reported correlation patterns call for targeted preventive strategies and intervention policies for mental and MSK disorders internationally. Special attention is needed among HICs.

Mental Ill-Health Risk Factors in the Construction Industry: Systematic Review

Mental ill health is a significant cause of suicide and disability worldwide. It has particularly affected the construction industry. The construction labor sectors in Australia and the United Kingdom have suicide rates 2 and 3.7 times higher, respectively, than their overall national averages, which has attracted the attention of researchers and the industry. However, few studies have examined the state of construction workers' mental health. This paper systematically reviews the existing body of knowledge on mental health in the construction industry. In total, 16 journal articles met inclusion criteria, and 32 risk factors (RFs) were deduced. The foremost RFs were related to job demand and job control. A conceptual framework and checklist to aid in better understanding these RFs were developed. In assessing mental health, the primary tool used was the Depression Anxiety Stress Scale. The findings of this study help to deepen the understanding of professional mental health assessment scales and relevant RFs and protective factors as used in the construction industry. The study concludes that stronger methodologies are needed for studies into RFs and protective factors in the construction industry.

The Comorbidity of Musculoskeletal Disorders and Depression: Associations with Working Conditions Among Hospital Nurses

Background: Musculoskeletal disorders (MSDs) are the leading cause of pain and disability among nurses and are frequently accompanied by depression. However, the association between the comorbidity of MSDs and depression and working conditions has not been studied, which was the aim of this study. Methods: In 2015, all nurses (n = 1,102) employed at a community hospital in the Northeast United States were invited to participate in this cross-sectional study. A survey was distributed in which participants were asked to report on MSDs, depressive symptoms, as well as subjective working conditions assessed including physical demands, psychological demands, decision authority, social support, and work-family conflict. Findings: 397 nurses responded (36%), and the prevalence of the comorbidity of MSDs and depression was 14.5%. Poisson regression (PR) models suggested that work-family conflict was associated with increased risk of the comorbidity (PR = 2.18; 95% confidence interval [CI] = 1.33-3.58), as was 8-hour night shift (PR = 2.77; 95% CI = [1.22, 6.31]) or 12-hour day shift (PR = 2.20; 95% CI = [1.07, 4.50]). Other working conditions were not directly associated with the comorbidity. Conclusions/Application to Practice: The comorbidity of MSDs and depression is prevalent among hospital nurses, and work-family conflict and working night shift or longer shifts were significantly associated with this. Effective workplace programs are needed to address nurses' working conditions to reduce their work-family conflict, thereby improving their musculoskeletal and mental health.

Occupational health in mental health services: a qualitative study

Purpose

The purpose of this paper is to explore occupational health (OH) clinicians’ perspectives on employee mental health in the mental health workplace in the English National Health Service.

Design/methodology/approach

Thematic analysis of data from seven semi-structured interviews is performed in this paper.

Findings

Three themes emerged under the core theme of “Situating OH services”: “the Uniqueness of the mental health service setting”, “the Limitations of OH services” and “the Meaning of mental health at work”. An important finding came from the first theme that management referrals in mental health may be due to disputes about workers’ fitness to face violence and aggression, a common feature of their working environment.

Research limitations/implications

This was a small scale study of a previously unresearched population.

Practical implications

These findings should be used to refine and standardise OH provision for mental healthcare workers, with a particular focus on exposure to violence and workers’ potential “lived experience” of mental illness as features of the mental health care workplace.

Originality/value

This is the first study to explore OH clinicians’ perspectives on the mental health service working environment.

Trajectories of mobility limitations over 24 years and their characterization by shift work and leisure-time physical activity in midlife

BACKGROUND

We aimed to investigate trajectories of mobility limitations (MLs) over a period of 24 years. In addition, we aimed to study how shift work and leisure-time physical activity (LTPA) in midlife predict assignment to MLs trajectories separately for those retired on statutory pensions (SPs) and on disability pensions (DPs).

METHODS

Subjects who responded MLs questionnaires (1985-2009, N = 3048) in Finnish Longitudinal Study on Aging Municipal Employees were included in this prospective cohort study. LTPA and shift work were measured during baseline. International Classification of Functioning was used to code MLs. Growth mixture modeling was used to identify the trajectories of MLs. Odds ratio (OR) and their 95% Confidence interval (CI) were assessed by using multinomial logistic regression.

RESULTS

We identified four trajectories of MLs, namely low persistent, low increasing, high decreasing and high persistent. Among the SP recipients, shift work with night shifts was associated with an increased risk (adjusted OR 1.49; 95% CI 1.03-2.14) of belonging to the high persistent MLs trajectory. The inactive LTPA (SP: OR 5.99, 95% CI 3.39-10.58, DP: OR 6.81, 95% CI 2.52-18.43) was similarly associated with high persistent MLs trajectory.

CONCLUSION

Nearly two-thirds of the people retired due to disability belonged to high MLs trajectory. High persistent MLs trajectory was associated with physical inactivity in midlife among those retired on SP and on DP. Shift work with night shift predicted high persistent MLs in SP strata. Active involvement in LTPA during midlife could be beneficial to spend MLs free later life.

Measuring biopsychosocial risk for back pain disability in chiropractic patients using the STarT back screening tool: a cross-sectional survey

Background

The Keele STarT Back Screening Tool (SBT), a 9-item questionnaire, screens for pain, physical functioning, fear-avoidance beliefs, catastrophizing, anxious thoughts, low mood, and bothersomeness in persons with back pain. SBT scores designate low, medium, or high risk for developing persistent disabling back pain. The primary study aim was to report the prevalence of SBT-calculated risk for back pain disability in US patients seeking chiropractic care.

Methods

The SBT questionnaire was administered to patients ≥18 years in 3 Chiropractic College outpatient teaching clinics in Iowa and Illinois (May 2017). Descriptive statistics were used to analyze respondent characteristics and prevalence of SBT-calculated risk subgroups. Binary logistic regression analysis was used to examine the relationship between respondent characteristics and SBT scores (including psychological subscores).

Results

Of 550 respondents, 496 completed the SBT; 392 (79%) scored low-risk, 81 (16%) medium-risk, and 23 (5%) high-risk. Mean (SD) age was 44.8 (15.9), 56.9% were female, 88.2% white, 62.6% employed, mean current pain was 2.9 (2.1) out of 10, and 62% reported symptom duration > 3 months. Eighteen percent of respondents reported anxious thoughts, 32% low mood, 41% ≥ 1 and 21% ≥ 3 SBT psychological risk factors. Respondents reporting higher average pain (OR = 1.8 [1.4, 2.3]) and pain severity (OR = 1.3 [1.0 to 1.6]) were more likely to score with medium or high risk. Respondents reporting mid back versus low back pain (OR = 0.2 [0.1, 0.7]), and those employed less than full-time versus full-time (0.2 [01, 0.5]) were less likely to score with medium or high risk. Respondents reporting higher average pain were more likely to report ≥1 psychological factor (OR = 1.8 [1.5, 2.0]). Respondents employed part-time were less likely to report ≥1 psychological factor than those employed full-time (OR = 0.4 [0.2, 0.7]).

Conclusion

The sample surveyed was less likely to score with medium or high risk for back pain disability than previous samples studied, perhaps due to differences in study design and sample characteristics. Rates of low mood and anxious thoughts indicate a need for future research to explore psychological factors among persons seeking chiropractic care.

Musculoskeletal Disorders: Prevalence and Associated Factors among District Hospital Nurses in Haiphong, Vietnam

Background

Musculoskeletal disorders (MSDs) are a major occupational health problematic among healthcare workers, and the prevalence is especially high among nurses. In high income countries, the prevention of MSDs is an occupational health priority. But in Vietnam, there is no data available among health professionals.

Objectives

To determine the prevalence and associated factors of musculoskeletal disorders among district hospital nurses in Haiphong city.

Material and Methods

A cross-sectional study was conducted on 1179 nurses working in 15 district hospitals using the Standardized Nordic Questionnaire.

Results

A very high prevalence of MSDs in the past 12 months (74.7%) and during the last 7 days (41.1%), with the two most common sites being the low back (44.4%) and neck (44.1%), was found; 37.8% complained that MSDs symptoms limit their work. When analyzing factors related to MSDs, the results showed that women were 2.1 times more likely to develop MSDs than men; people with a previous history of MSDs were more likely to develop MSDs symptoms in the past 12 months than those with no history (OR = 7.1); nurses with symptoms of psychological distress and frequent absenteeism in the workplace had a higher prevalence of MSDs compared to the rest (p<0.001).

Conclusions

Due to the high prevalence of MSDs among nurses in district hospitals in Haiphong, preventive actions are needed to improve the working conditions and to raise the awareness of nurses about MSDs prevention.

Inter-rater reliability of direct observations of the physical and psychosocial working conditions in eldercare: An evaluation in the DOSES project

The aim of the study was to develop and evaluate the reliability of the "Danish observational study of eldercare work and musculoskeletal disorders" (DOSES) observation instrument to assess physical and psychosocial risk factors for musculoskeletal disorders (MSD) in eldercare work. During 1.5 years, sixteen raters conducted 117 inter-rater observations from 11 nursing homes. Reliability was evaluated using percent agreement and Gwet's AC1 coefficient. Of the 18 examined items, inter-rater reliability was excellent for 7 items (AC1>0.75) fair to good for 7 items (AC1 0.40-0.75) and poor for 2 items (AC1 0-0.40). For 2 items there was no agreement between the raters (AC1 <0). The reliability did not differ between the first and second half of the data collection period and the inter-rater observations were representative regarding occurrence of events in eldercare work. The instrument is appropriate for assessing physical and psychosocial risk factors for MSD among eldercare workers.

Effectiveness of conservative interventions for sickness and pain behaviors induced by a high repetition high force upper extremity task

Background

Systemic inflammation is known to induce sickness behaviors, including decreased social interaction and pain. We have reported increased serum inflammatory cytokines in a rat model of repetitive strain injury (rats perform an upper extremity reaching task for prolonged periods). Here, we sought to determine if sickness behaviors are induced in this model and the effectiveness of conservative treatments.

Methods

Experimental rats underwent initial training to learn a high force reaching task (10 min/day, 5 days/week for 6 weeks), with or without ibuprofen treatment (TRHF vs. TRHF + IBU rats). Subsets of trained animals went on to perform a high repetition high force (HRHF) task for 6 or 12 weeks (2 h/day, 3 days/week) without treatment, or received two secondary interventions: ibuprofen (HRHF + IBU) or a move to a lower demand low repetition low force task (HRHF-to-LRLF), beginning in task week 5. Mixed-effects models with repeated measures assays were used to assay duration of social interaction, aggression, forepaw withdrawal thresholds and reach performance abilities. One-way and two-way ANOVAs were used to assay tissue responses. Corrections for multiple comparisons were made.

Results

TRHF + IBU rats did not develop behavioral declines or systemic increases in IL-1beta and IL-6, observed in untreated TRHF rats. Untreated HRHF rats showed social interaction declines, difficulties performing the operant task and forepaw mechanical allodynia. Untreated HRHF rats also had increased serum levels of several inflammatory cytokines and chemokines, neuroinflammatory responses (e.g., increased TNFalpha) in the brain, median nerve and spinal cord, and Substance P and neurokinin 1 immunoexpression in the spinal cord. HRHF + IBU and HRHF-to-LRLF rats showed improved social interaction and reduced inflammatory serum, nerve and brain changes. However, neither secondary treatment rescued HRHF-task induced forepaw allodynia, or completely attenuated task performance declines or spinal cord responses.

Conclusions

These results suggest that inflammatory mechanisms induced by prolonged performance of high physical demand tasks mediate the development of social interaction declines and aggression. However, persistent spinal cord sensitization was associated with persistent behavioral indices of discomfort, despite use of conservative secondary interventions indicating the need for prevention or more effective interventions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12868-017-0354-3) contains supplementary material, which is available to authorized users.